Methodology

What we calculate

• Gross pay conversions between hourly and annual pay using hours per week and paid weeks per year.
• Federal income tax estimates using a progressive bracket model and the standard deduction for single filers or married filing jointly.
• FICA (Social Security and Medicare) estimates using wage-base and threshold rules.
• State income tax estimates using published brackets when available and an effective-rate fallback for gaps.

What we do not include

• Tax credits (including child tax credit and earned income credit).
• Itemized deductions and most above-the-line adjustments beyond the standard deduction.
• Pre-tax benefits (health insurance, HSA/FSA), retirement contributions, garnishments, or employer-specific payroll policies.
• City, county, or local income taxes, and special district surcharges.
• Overtime multipliers, shift differentials, commissions, bonuses, or irregular pay timing.

Data sources and update cadence

We keep tax inputs in versioned JSON files by tax year and display the tax year used on calculator pages. When tax rules change, we update the config and ship a new build; older years may remain available for comparison.

• Federal brackets and standard deduction: IRS annual inflation adjustments and official tables.
• FICA parameters: Social Security wage base and Medicare rate/threshold guidance.
• State tax inputs: state revenue department publications (bracket tables with an effective-rate fallback where needed).

How to use these pages

Use the estimates to compare scenarios (states, pay rates, or salaries) on a consistent set of assumptions. For decisions that depend on exact withholding, confirm the numbers using your pay stub, payroll provider, or official tax guidance.